The present disclosure relates to a developing roller used for image forming apparatuses utilizing an electrophotographic scheme, such as a copier, a printer, a facsimile machine, and a multifunction printer that is a combination of a copier, a printer, and a facsimile machine, and a developing apparatus and an image forming apparatus using the developing roller.
In an electrophotographic process, an electrostatic latent image is formed on a photoreceptor, and the electrostatic latent image is developed into a toner image by a developing apparatus. The toner image on the photoreceptor is transferred to a sheet, and the toner image on the sheet is fixed by a fixing apparatus. An example of such a developing apparatus used for an image forming apparatus forms and holds a two-component developer containing a magnetic carrier and toner, on a magnetic roller as a magnetic brush, uses the magnetic brush to form a thin toner layer on the developing roller, and feeds the toner to the photoreceptor to develop the electrostatic latent image formed on the photoreceptor in a noncontact manner.
It is known that, in a developing apparatus based on this developing scheme, a surface of a developer carrier (developing roller) is provided with roughness to reduce the contact area between the developing roller and toner, thus improving development properties.
As a method for providing the surface of the developer carrier (developing roller) with roughness, for example, the following are known: a method of applying surface roughness by mechanically roughening a surface of a support base providing the roller (sandblasting or the like) and a method of applying surface roughness to a roller with a resin layer formed on the support base and including a binder resin, by adding fine particles s to the resin layer.